Many of the far-right activists, clad in red and white, hoisted the red, white and black flag of Hitler's Third Reich. One group carried a sign that proclaimed, "I regret nothing: National Socialists Berlin."

"There were reports of injuries when some stones and bottles were thrown by counter demonstrators at the far-right demonstrators," Berlin police spokesman Thilo Cablitz told Reuters. "At least one police officer was injured. But the event is still going on and we're still compiling the numbers."

About 2,300 police officers were on duty to prevent violence at the Berlin event and a separate march by less than 50 people in the Berlin suburb of Spandau, where Hess, a former deputy of Germany's wartime dictator Adolf Hitler, served a life sentence handed down at the Nuremberg war crimes trials.

A broad mix of counter demonstrators staged non-violent sit-ins at intersections along the march route in the Berlin neighborhood of Lichtenberg, while others gathered to shout at the neo-Nazi demonstrators.

Germany has tough laws that ban use of symbols of the Nazi regime, such as the swastika flag, but the far-right has grown stronger in recent years after the arrival of more than a million mostly Muslim migrants beginning in 2015.